Biology subjects

Avril, A.

Publications and source records attributed to Avril, A..

4 recordsLinked to original sources

bioRxiv2024

Do morphologically distinct groups correspond to reproductively isolated species? A case study in Myrmica ants from Switzerland

The most widely used definition of a species is that it is reproductively isolated from other populations. Yet, most species are described on the basis of morphological criteria, and reproductive isolation is seldom tested. Using the ant genus Myrmica Latreille (Hymenoptera, Formicidae) as a model, we ask whether species described as distinct based on (often subtle) morphological differences indeed form reproductively isolated lineages. We collected and morphologically identified 918 Myrmica ants from a 3212 km2 area in Switzerland. We then combined DNA barcoding (based on COI) and RAD sequencing to identify genetically isolated lineages. Out of the 14 morphological species identified, 13 formed genetically differentiated lineages, while the last one was not supported by our genetic data. Overall, the morphological identification was congruent with genetic lineage delineation for 94.9% of individuals. Our dataset also allowed us to screen for cryptic lineages in the five most frequent species, including in M. scabrinodis where cryptic lineages were previously suggested, but we found no evidence for cryptic species. Overall, our results indicate that morphology parallels genetic isolation in the studied species. However, an integrative approach combining morphological identification with nuclear marker genotyping is necessary for confident species identification of all individuals. Finally, our results provide a library of validated COI barcodes for future Myrmica specimen identification.

evolutionary biology↗

bioRxiv2024

Evaluation of Silica and Bioglass Nanomaterials in Pulp-Like Living Materials

Although silicon is a widespread constituent in dental materials, its possible influence on teeth formation and repair remains largely unexplored. Here we have studied the effect of two silicic acid-releasing nanomaterials, silica and bioglass, on a living model of pulp consisting of dental pulp stem cells seeded in dense type I collagen hydrogels. Silica nanoparticles and released silicic acid had little effect on cell viability and mineralization efficiency but impacted metabolic activity, delayed matrix remodeling and led to heterogeneous cell distribution. Bioglass improved cell metabolic activity and led to a homogenous dispersion of cells and mineral deposits within the scaffold. These results suggest that the presence of calcium ions in bioglass is not only favorable to cell proliferation but can also counter-balance the negative effects of silica and silicic acid. Both chemical and biological processes should therefore be considered when investigating the effect of silicon-containing materials on dental tissues.

bioengineering↗

bioRxiv2024

LEVERAGING CITIZEN SCIENCE TO ASSESS RICHNESS, DIVERSITY, AND ABUNDANCE IN ANT COMMUNITIES

AO_SCPLOWBSTRACTC_SCPLOWCitizen science is a key resource in overcoming the logistical challenges of monitoring biodiversity. While datasets collected by groups of volunteers typically have biases, recent methodological and technological advances provide approaches for accounting for such biases, particularly in the context of modelling species distributions and diversity. Specifically, data integration techniques allow for the combination of scientifically collected datasets with haphazardly sampled presence-only datasets created by most citizen science initiatives. Here, we use a hierarchical Bayesian framework to integrate a set of ant presences collected by citizen scientists in the Vaud canton (Switzerland) with ant colony density data collected concurrently in the same region following a scientific sampling design. The community-level Poisson point process model included species-specific responses to the local (1.2 m2) and regional (1 km2) environment, with the presence-only samples incorporated at the regional scale to predict local and regional ant communities. At the regional scale, species richness followed a hump-shaped pattern and peaked near 1000 m while abundance increased with elevation. Low elevation and montane ant communities were composed of distinct species assemblages. At the local scale, the link between elevation and richness, diversity, and abundance was weak. At low elevations, local plots varied both in total abundance and species composition, while at higher elevations, the species composition was less variable. The citizen science dataset showed a general tendency toward under-representation of certain species, and heavy spatial sampling bias. Nonetheless, the inclusion of the citizen science data improved predictions of local communities, and also reduced susceptibility to over-fitting. Additionally, the citizen science dataset included many rare species not detected in the structured abundance dataset. The model described here illustrates a framework for capitalizing on the efforts of citizen scientists to better understand the patterns and distribution of biodiversity.

ecology↗

bioRxiv2021

Whole-genome analysis of multiple wood ant population pairs supports similar speciation histories, but different degrees of gene flow, across their European range

The application of demographic history modeling and inference to the study of divergence between species is becoming a cornerstone of speciation genomics. The demographic history is usually reconstructed by analysing a single population from each species, assuming that the divergence history inferred between these populations represents the actual speciation history. However, this assumption is rarely explicitly tested, and it may not be met when species diverge with gene flow. For instance, secondary contact between two species after a range expansion may be confined into a specific geographic region. In this study, we tested to what extent the divergence history inferred from two heterospecific populations would vary depending on their geographic locations, using mound-building red wood ants. The wood ant species Formica polyctena and F. aquilonia have contrasting distributions in Europe and naturally hybridize in Finland. We first performed whole-genome resequencing of 20 individuals sampled in multiple populations across both species ranges. We then reconstructed the divergence histories of distinct heterospecific population pairs using a coalescent-based approach. We found that the analysis of these different population pairs always supported a scenario of divergence with gene flow, suggesting that species divergence started in the Pleistocene (ca. 500 kya) and occurred with continuous asymmetrical gene flow from F. aquilonia to F. polyctena until a recent time, when migration stopped (2-19 kya, depending on the population pair considered). However, we found support for contemporary gene flow in the sympatric population pair from Finland, where hybrids have been described. Overall, our results suggest that divergence histories reconstructed from a few individuals may be reliable and applicable at the species level. Nonetheless, the geographical context of populations chosen to represent their species should be taken into account, as it may affect estimates of migration rates between species when gene flow is heterogeneous across their geographical ranges.

evolutionary biology↗